==================================================================
BUG: KASAN: slab-use-after-free in ax25_heartbeat_expiry+0x115/0x140 net/ax25/ax25_timer.c:127
Read of size 4 at addr ffff888077e42460 by task syz.0.4898/25916
CPU: 1 UID: 0 PID: 25916 Comm: syz.0.4898 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xba/0x230 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
ax25_heartbeat_expiry+0x115/0x140 net/ax25/ax25_timer.c:127
call_timer_fn+0x192/0x5e0 kernel/time/timer.c:1748
expire_timers kernel/time/timer.c:1799 [inline]
__run_timers kernel/time/timer.c:2374 [inline]
__run_timer_base+0x652/0x8b0 kernel/time/timer.c:2386
run_timer_base kernel/time/timer.c:2395 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2405
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:console_flush_one_record arch/x86/include/asm/irqflags.h:-1 [inline]
RIP: 0010:console_flush_all+0x801/0xb20 kernel/printk/printk.c:3343
Code: ff ff e8 72 c3 20 00 90 0f 0b 90 e9 85 fc ff ff e8 64 c3 20 00 e8 9f 7a 0e 0a 48 85 db 74 c0 e8 55 c3 20 00 fb 48 8b 5c 24 08 <48> 8b 44 24 20 42 80 3c 20 00 4c 8b 74 24 18 74 08 4c 89 f7 e8 66
RSP: 0018:ffffc9000405f3e0 EFLAGS: 00000283
RAX: ffffffff81a49a9b RBX: ffffc9000405f540 RCX: 0000000000080000
RDX: ffffc9001f155000 RSI: 000000000000193c RDI: 000000000000193d
RBP: ffffc9000405f4f0 R08: ffffffff903215b7 R09: 1ffffffff20642b6
R10: dffffc0000000000 R11: fffffbfff20642b7 R12: dffffc0000000000
R13: 0000000000000001 R14: 0000000000000000 R15: ffffffff8f20f3c0
__console_flush_and_unlock kernel/printk/printk.c:3373 [inline]
console_unlock+0xd1/0x1c0 kernel/printk/printk.c:3413
vprintk_emit+0x485/0x560 kernel/printk/printk.c:2479
_printk+0xdd/0x130 kernel/printk/printk.c:2504
set_target_v0_checkentry+0x3f1/0x500 net/netfilter/xt_set.c:249
xt_check_target+0x4a8/0xbf0 net/netfilter/x_tables.c:1065
check_target net/ipv4/netfilter/ip_tables.c:510 [inline]
find_check_entry net/ipv4/netfilter/ip_tables.c:552 [inline]
translate_table+0x1881/0x2110 net/ipv4/netfilter/ip_tables.c:716
do_replace net/ipv4/netfilter/ip_tables.c:1137 [inline]
do_ipt_set_ctl+0x9f5/0xe00 net/ipv4/netfilter/ip_tables.c:1635
nf_setsockopt+0x26f/0x290 net/netfilter/nf_sockopt.c:101
do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2381
__sys_setsockopt net/socket.c:2406 [inline]
__do_sys_setsockopt net/socket.c:2412 [inline]
__se_sys_setsockopt net/socket.c:2409 [inline]
__x64_sys_setsockopt+0x13d/0x1b0 net/socket.c:2409
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c3259c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1c333f6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f1c32816360 RCX: 00007f1c3259c819
RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f1c32632c91 R08: 0000000000000430 R09: 0000000000000000
R10: 0000200000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c328163f8 R14: 00007f1c32816360 R15: 00007fffc081a468
Allocated by task 24858:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5380
kmalloc_noprof include/linux/slab.h:950 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
ax25_dev_device_up+0x54/0x5f0 net/ax25/ax25_dev.c:57
ax25_device_event+0x127/0x8a0 net/ax25/af_ax25.c:143
notifier_call_chain+0x1ad/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2287 [inline]
call_netdevice_notifiers net/core/dev.c:2301 [inline]
__dev_notify_flags+0x1a9/0x310 net/core/dev.c:9849
netif_change_flags+0xe8/0x1a0 net/core/dev.c:9878
dev_change_flags+0x130/0x260 net/core/dev_api.c:68
dev_ioctl+0x7b4/0x1150 net/core/dev_ioctl.c:814
sock_do_ioctl+0x23e/0x320 net/socket.c:1327
sock_ioctl+0x5c6/0x7f0 net/socket.c:1434
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 17536:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2685 [inline]
__rcu_free_sheaf_prepare+0x129/0x290 mm/slub.c:2954
rcu_free_sheaf+0x31/0x200 mm/slub.c:5811
rcu_do_batch kernel/rcu/tree.c:2617 [inline]
rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
handle_softirqs+0x22a/0x840 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0xca/0x220 kernel/softirq.c:735
irq_exit_rcu+0x9/0x30 kernel/softirq.c:752
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1061 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1061
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
The buggy address belongs to the object at ffff888077e42400
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 96 bytes inside of
freed 256-byte region [ffff888077e42400, ffff888077e42500)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888077e43c00 pfn:0x77e42
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88813fe2cb40 ffffea0000d9ed10 ffffea0000a93c10
raw: ffff888077e43c00 0000000800100008 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fe2cb40 ffffea0000d9ed10 ffffea0000a93c10
head: ffff888077e43c00 0000000800100008 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0001df9081 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6021, tgid 6019 (syz.1.24), ts 99646929105, free_ts 99281714445
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
prep_new_page mm/page_alloc.c:1897 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
alloc_slab_page mm/slub.c:3292 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3481
new_slab mm/slub.c:3539 [inline]
refill_objects+0x331/0x3c0 mm/slub.c:7175
refill_sheaf mm/slub.c:2812 [inline]
__pcs_replace_empty_main+0x2e6/0x730 mm/slub.c:4615
alloc_from_pcs mm/slub.c:4717 [inline]
slab_alloc_node mm/slub.c:4851 [inline]
__do_kmalloc_node mm/slub.c:5259 [inline]
__kmalloc_noprof+0x474/0x760 mm/slub.c:5272
kmalloc_noprof include/linux/slab.h:954 [inline]
kzalloc_noprof include/linux/slab.h:1188 [inline]
hash_ipportnet6_add+0x1634/0x2eb0 net/netfilter/ipset/ip_set_hash_gen.h:950
hash_ipportnet6_uadt+0xa88/0xe00 net/netfilter/ipset/ip_set_hash_ipportnet.c:504
call_ad+0x18d/0xb60 net/netfilter/ipset/ip_set_core.c:1751
ip_set_ad+0x824/0x9d0 net/netfilter/ipset/ip_set_core.c:1841
nfnetlink_rcv_msg+0xc03/0x12c0 net/netfilter/nfnetlink.c:300
netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
nfnetlink_rcv+0x2c0/0x27b0 net/netfilter/nfnetlink.c:667
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x75c/0x8e0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
page last free pid 5875 tgid 5875 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1433 [inline]
__free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
__slab_free+0x263/0x2b0 mm/slub.c:5573
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4538 [inline]
slab_alloc_node mm/slub.c:4866 [inline]
__do_kmalloc_node mm/slub.c:5259 [inline]
__kmalloc_node_track_caller_noprof+0x493/0x7b0 mm/slub.c:5368
kmalloc_reserve net/core/skbuff.c:635 [inline]
__alloc_skb+0x2c1/0x7d0 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6734
sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:2998
unix_dgram_sendmsg+0x460/0x18d0 net/unix/af_unix.c:2131
sock_sendmsg_nosec net/socket.c:787 [inline]
__sock_sendmsg net/socket.c:802 [inline]
sock_write_iter+0x49b/0x4f0 net/socket.c:1254
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61d/0xb90 fs/read_write.c:688
ksys_write+0x150/0x270 fs/read_write.c:740
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888077e42300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888077e42380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888077e42400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888077e42480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888077e42500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess), 1 bytes skipped:
0: ff ljmp (bad)
1: e8 72 c3 20 00 call 0x20c378
6: 90 nop
7: 0f 0b ud2
9: 90 nop
a: e9 85 fc ff ff jmp 0xfffffc94
f: e8 64 c3 20 00 call 0x20c378
14: e8 9f 7a 0e 0a call 0xa0e7ab8
19: 48 85 db test %rbx,%rbx
1c: 74 c0 je 0xffffffde
1e: e8 55 c3 20 00 call 0x20c378
23: fb sti
24: 48 8b 5c 24 08 mov 0x8(%rsp),%rbx
* 29: 48 8b 44 24 20 mov 0x20(%rsp),%rax <-- trapping instruction
2e: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
33: 4c 8b 74 24 18 mov 0x18(%rsp),%r14
38: 74 08 je 0x42
3a: 4c 89 f7 mov %r14,%rdi
3d: e8 .byte 0xe8
3e: 66 data16